1. Field of the Invention
The present invention pertains to environmentally sealed backshells for electrical connectors of the plug and receptacle type.
2. Description of the Prior Art
The present invention pertains to ruggedized mating electrical connectors, each of which are enclosed in an outer metallic shell. Specifically, each connector receives a dielectric insert in which a plurality of electrical terminals are mounted. Such electrical connectors are typically required in the aircraft ground support and automotive industries, as well as in machinery and outdoor, unprotected environments. In these applications cable backshells are frequently employed including a rigid outer shell threadingly engaged onto the cable entry end of the mateable connector halves or frontshells. Backshells typically provide strain relief means to protect against cable shocks or pull-out which may cause damage to the frontshell connector components.
In many environments, water or moisture present in the air or in contact with the connector present a problem to the electrical connections within a mated electrical connector pair. Accordingly, as a second important feature, mated connector pairs of this type provide an arrangement for sealing the conductor-entry end of each connector part, as well as providing sealing at the mating face of the connector part. An example of such a sealing arrangement is shown in commonly owned U.S. Pat. No. 4,472,012. In that arrangement, each connector insert is made of a resilient elastomeric material effective for not only receiving and mounting an electrical terminal therein, but also for providing a sealing interface with the complementary connectors of the assembled pair.
Other sealing arrangements include an "O"-ring to effect sealing at the mating face between the backshell and the cable end of the frontshell. Seals of this and similar types require a well defined, rotatably engageable, mating face at the connector end to which the seal is mated. However, several different configurations for the coupling interface between the backshell and frontshell are encountered. One of these types presents a relatively smooth end wall on the frontshell cable end to engage the sealing member. Another type is illustrated in U.S. Pat. No. 4,536,048, and includes serrations on the frontshell cable end to provide anti-decoupling.
In the past, different backshells were required to mate with the different types of frontshell cable end configurations. However, to reduce inventory and to provide a multiple purpose backshell, a backshell sealing arrangement for mating with both the serrated type as well as smooth wall type frontshell cable ends is desired.
Due to increasing miniaturization of environmental connectors, one well-known backshell sealing method is no longer a viable alternative to the connector manufacturer. The sealing arrangement referred to is one in which a rigid backshell is threaded onto a radially inner cable end on a front shell member. The threaded portion of the backshell includes a pocket-like recess for receiving an "O"-ring. This O-ring makes contact with the threaded external threads of the cable end of the front shell. However, as mentioned above, with increasing miniaturization of environmental connectors this mating arrangement is not available when the axially extending threaded portion of the backshell must be reduced to a minimum dimension. Typically, only three or four threads can be located on the backshell and the space generally correpsonding to two threads in size can no longer be provided for the O-ring. However, it is desirable to provide mating of the same backshell with a variety of front shell configurations having smooth or serrated mating end walls and/or protruding or recessed insert portions located interior of the external threads of the front shell adjacent the cable entry face thereof.
Accordingly, it is an object of the present invention to provide a versatile backshell seal for sealing the backshell interface with a plurality of frontshell configurations.